Cellular communications systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular telephones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices and the different types of devices available to users. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly send and receive electronic mail (email) messages and access the Internet via a cellular network and/or a wireless local area network (WLAN), for example.
Accordingly, there is a continual evolution in cellular communications formats that can not only provide desired voice communication coverage, but also which can provide higher throughputs for data intensive applications such as Web browsing, digital file transfer, etc. As a result, different cellular protocols or formats are often layered upon one another as technology progresses. One example is in Code Division Multiple Access (CDMA) systems, such as CDMA2000 systems. CDMA2000 is a hybrid system that uses both second and third generation (3G) formats to cover both voice and data communications. More particular, the CDMA 1×RTT (1×) format is the core CDMA2000 wireless air interface standard and is the basic or default service communications format provided by cellular base stations for both voice and data.
On the other hand, Evolution-Data Optimized (EVDO) is a 3G CDMA telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. However, CDMA 1× and EVDO may utilize different frequency bands, or they may both share the same frequency bands but use different coding. Moreover, cellular network providers often do not have the infrastructure in place at all of their base stations to provide seamless EVDO coverage. As such, it becomes necessary for CDMA cellular devices to monitor paging channels from different cellular base stations to fill in these “holes” in the network, to provide voice coverage (as EVDO is generally not well suited to voice traffic), and to determine when the higher data throughput EVDO option is available to provide enhanced performance.
One exemplary system for monitoring paging channels from different network formats is disclosed in U.S. patent pub. No. 2006/0182069. More particularly, the system permits a network, such as a data only network (e.g., CDMA2000 1×-EVDO), with which a mobile terminal is not currently communicating to notify the mobile terminal that the network desires to establish communication with the mobile terminal, even in instances in which the mobile terminal is actively communicating via another network, such as a voice and data network (e.g., CDMA2000 1×) and has stopped monitoring for paging messages. The mobile terminal can then end communications with the network with which it has been previously communicating and commence communications with the other network that has transmitted the paging message. For example, a mobile terminal may terminate voice communications via a voice and data network in order to receive an MMS message via a data only network upon receiving notification that the data only network desires to establish a communications session with the mobile terminal.
Despite the advantages of such approaches, further developments may be desirable in mobile wireless communications devices for monitoring the availability of different communications formats, particularly cellular devices.